about how long does it take for a tank to cycle? my tank is 2.5 gallons. and it still has the weird smell...

i'm just wondering when i can do a full tank change. (i'm currently doing around 25% - 30% water changes every other day) because i'd really love to kinda rinse off the gravel and stuff to get rid of the smell or at least minimize it.

unfortunately i don't have the liquid test kit. i've been meaning to get one but i dont have the thirty bucks :(
i'm monitering my fish very closely though and she's very active, her colors are vibrant, and she eats like crazy.